Signal amplitude responsive trigger circuits for quantizing



Nov. 1, 1949. CUNNlNGHAM 2,486,391

SIGNAL AMPLITUDE RESPONSIVE TRIGGER CIRCUITS FOR QUANTIZING Filed Sept. 12, 1945 2 Sheets-$heet 1 5 7/22 "4am 191M Armm/LW Nov. 1, 1949. R. D. CUNNINGHAM 2,486,391

" zSIGNAL AMPLITUDE RESPONSIVE TRIGGER CIRCUITS FOR QUANTIZING Filed Sept. 12, 1945 2 Sheets-Sheet 2 5 ATTU/Q/VE) Patented Nov. 1, 1949 SIGNAL AMPLITUDE RESPONSIVE TRIGGER CIRCUITS FOR QUANTIZING Rhean D. Cunningham, Arlington County, Va.

Application September 12, 1945,'Serial No. 616,483

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) 4 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention is in electrical apparatus and particularly is a circuit adapted to take a fluctuating direct current signal, sample the signal at predetermined intervals, and supply an output signal on one of a plurality of output leads, the selection of the lead depending upon the value of the input signal at the instant of sampling. The circuit may hereinafter be referred to as a quantizer.

The principal object of the invention is to provide a novel circuit which will react substantially instantaneously to a change of input signal value by selecting a different one out of a plurality of outputs.

Another object is to provide a circuit which will react substantially instantaneously to a change of input signal by delivering a maximum output signal to a selected line, the selection of the line being a function of the value of the input signal at a particular instant.

An additional object is to provide a novel direct current stepping circuit.

Other objects will be apparent from a reading of the following specification and claims.

In the drawings:

Figure 1 is a schematic diagram of the novel quantizing circuit of my invention; and

Figure 2 is a diagram of the stepping circuit.

The invention may be readily understood by reference to the drawings and particularly to Figure 1 wherein may be seen ten vacuum triodes it through It direct current coupled together in pairs in the nature of Eccles-Jordan trigger circuits. The exact number of triode stages will depend upon the characteristics desired in the circuit, namely whether it is to be capable of establishing six output values (as in the embodiment shown) or some other number.

The plate of triode I is connected to output lead 20 through a decoupling resistance 2| and to ground through resistor 22. Triodes II and i2 are connected to output lead 25 through decoupling resistors 25 and 21, respectively, and to ground through resistor 23. Triode pairs iB M, l5-l5, and Il-IB are similarly connected to outputs 3B, 35, and 40 while triode I9 is connected to output lead 45.

Considering the pair of triodes H-l2, if one is conducting and the other is not, a low value of voltage is developed across resistor 28. If neither is conducting, the maximum voltage is developed. Similar effects are obtained with the other pairs of triodes. With regard to triodes l6 and I9, a low value of voltage appears on their output lines when the tubes are conducting, and maximum voltage is developed when the tubes are cut off. The arrangement, which will be described more specifically below, is such that regardless of the value of the input voltage one and only one output line will carry a maximum voltage signal at any instant.

The varying voltage which is to be treated by this circuit is applied through line 50. The circuit is intended to be exposed to the input voltage for a short period of time, and the switch 52, shown as manually operable, is in fact normally a high speed mechanical or electronic device. During the exposure time, the circuit of my invention detects the value of the input signal, indicates it as explained by putting a maximum value signal on one of the output lines, and maintains its condition until a restoring (positive) pulse is received over line 53. Where high speed operation is desired, synchronization of any desired type may be supplied for the switch 52 and the restoring means.

With the circuit in its zero condition or when the input voltage is of the first step level value the step values being chosen arbitrarilytriodes ll, l3, l5, H, and H] are conducting while triodes l0, l2, l4, l6, and i8 are cut off. The tubes of the latter group are difierently biased by means of variable resistors '55, 56, 51, 58, and 59, the exact values thereof depending upon the characteristics desired. In zero condition, maximum voltage will appear on output line 20, only,

since tube l9 and one tube of each of the pairs of tubes are conducting, whereas tube I0 is cut off.

Should the input signal value rise to a point between the second and third step level values, the grid of triode I0 is raised positively to such a point that the tube will conduct, larger cathode resistance values preventing conduction in the other tubes. As tube l0 conducts, a negative pulse is obtained from its late and furnished to the grid of triode ll, thereby cutting off this latter tube. At this instant, both tube II and tube l2 are cut ofi, whereas triodes l0, l3, l5, l1, and H) are conducting, and maximum voltage is developed on output 25.

As the value of the input signal rises to the third step level, triodes l0 and I2 conduct; In either cuts off or holds cut oil triode I I, while l2 cuts off triode I3, thereby causing a maximum voltage to appear on output 30. As the operation continues,

a point will be reached at whichtubes I0, l2, I4, I6, and I8 all are conducting, whereas tubes H, l3, l5, l1, and [9 are cut off, tube I9 being extinguished by the action of triode I8, and in this situation maximum Voltage appears on output 45, this representing the sixth voltage step level value.

Extinction or substantial change downwardly in the value of the input signal leaves the circuit locked in the condition assumed at the instant of sampling, and this condition will be maintained until a positive restoring pulse is delivering to the grids of tubes H, l3, l5, l1, and I9. Upward change in the input voltage will modify the output of the circuit.

The circuit may be converted into a direct current stepping circuit by the modifications shown in Figure 2 wherein any signals on output lines 20, 25, 30, 35, 40, and 45 are caused to produce voltage drops of various predetermined magnitudes across resistor 60.

The foregoing description is in specific terms, and many modifications will readily suggest themselves. The invention should not, in other Words, be considered as limited to the exact apparatus shown and described, but, instead, for the true scope thereof, reference should be had to the appended claims.

I claim:

1. A circuit of the nature described comprising a plurality of trigger circuits each having two electrically stable conditions and each having an initially on tube and an initially ofi tube, a power supply connected to the plates of said tubes, a source of biasing voltage, and means connecting the same to said initially off tubes to condition the same for conduction at different and successively higher input signal values, an output line connected to one of said initially oil tubes, an output line connected to one of said initially on tubes, a plurality of output lines each connected to an initially off tube of one trigger circuit and an initially on tube of another trigger circuit, a source of input signals connected in parallel to said initially off tubes, and a source of additional signals and means for connecting the same to said initially on tubes to promote conduction in any such tube the initial condition of which has been altered.

2. A circuit of the nature described comprising a plurality of trigger circuits each having two electrically stable conditions and each having an initially on tube and an initially off tube, a power supply connected to the plates of said tubes, a source of biasing voltage, and means connecting the same to said initially off tubes to condition the same for conduction at different successively higher input signal values, an output line connected to one of said initially off tubes, an output line connected to one of said initially on tubes, a plurality of output lines each connected to an initially off tube of one trigger circuit and an initially on tube of another trigger circuit, a source of input signals and means for sampling the same and for connecting the instantaneous voltages thereof in parallel to said initially off tubes, and a source of additional signals and means for connecting the same initially on tubes to promote conduction in any such tube the initial condition of which has been altered.

3. A circuit of the nature described comprising a plurality of trigger circuits each having two electrically stable conditions and each having an initially on tube and an initially ofi tube, a power supply connected to the plates of said tubes, a source of biasing voltage, and means connecting the same to said initially on" tubes to condition the same for conduction at different and successively higher input signal values, a voltage dividing network, an output line connected to one of said initially oiT tubes and to one point on said voltage dividing network, an output line connected to one of said initially on tubes and to a second point on said voltage dividing network, a plurality of output lines each connected to an initially off tube of one trigger circuit and an initially on tube of another trigger circuit and each connected to a different point on said voltage dividing network, a source of input signals connected in parallel to said initially ofi tubes, and a source of additional signals and means for connecting the same to said initially on tubes to promote conduction in any such tube the initial condition of which has been altered.

4. A circuit of the nature described including two trigger circuits each having two electrically stable conditions and each having an initially on tube and an initially oif tube the initially off tube of the second trigger circuit being biased more negative than the initially oif tube of the first trigger circuit, a voltage dividing network, an output line for the initially off tube of one of said trigger circuits, an output line for the initially on tube of the second trigger circuit, an output line common to the initially on tube of said one trigger circuit and to the initially off tube of the second trigger circuit, each of said output lines being connected to a different point on said voltage dividing network, a source of input signals connected to said initially off tubes in parallel, and a source of additional signals and means for connecting the same to said initially on tubes in parallel to promote conduction in any tube the initial condition of which'has been altered.

RI-IEAN D. CUNNINGHAM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,312,357 Ordquist et a1 Mar. 2, 1943 2,390,608 Miller et a1 Dec. 11, 1945 2,402,917 Miller June 25, 1946 2,407,320 Miller Sept. 10, 1946 OTHER REFERENCES Review of Scientific Instructions, Feb. 1941 issue, pp. 102, 103. Copy available for reference in Division 10 250-36-13.1. 

